Analysis of epsilon germline transcripts and IL-4 mRNA expression in the adenoids suggests local IgE switching

Background: We have previously observed more frequent occurrence of IgE(+) and Fc epsilon RI+ cells in adenoids of atopic than nonatopic children. To investigate the hypothesis that the adenoids are involved in IgE production, we analyzed the levels of epsilon germline (epsilon GL), IL-4, and IFN-gamma transcripts in the adenoids in relation to atopy and presence of ear disease. Methods: Adenoidectomy was performed on 19 atopic and 18 nonatopic children (median age 5 years, range 2-12 years) suffering from otitis media with effusion (OME) (n = 16) or obstructive adenoids hyperplasia (AH) (n = 21). The levels of epsilon GL transcripts, IL-4, and IFN-gamma mRNA were analyzed by competitive reverse transcriptase-PCR. Results: epsilon GL transcript levels in the adenoids were found to be dependent on IL-4 mRNA expression (P < 0.01) and serum IgE levels (P < 0.05) (R-2 = 0.32, n = 37). IL-4 mRNA expression was associated with epsilon GL transcript levels (r(s) = 0.32, P = 0.05, n = 37), especially among patients with AH (r(s) = 0.53, P = 0.01, n = 21). No significant differences in IL-4 and IFN-gamma mRNA levels were observed between the groups. Conclusions: This study supports an IL-4-induced class switch to IgE production in the adenoids that might be of importance for inflammatory reactions in the upper respiratory tract.